Regulatory mechanisms for IgE antibody response will be studied in the mouse as well as in vitro culture system using rabbit lymph node cells. Soluble antigen which stimulate T cells, but not B cells, will be prepared and effect of such antigen on an on-going IgE antibody response will be studied in the mouse. In addition, attempts will be made to prime mouse T cells in vitro, and helper function of the primed cells will be studied by adoptive transfer technique. Using rabbit lymph node cells primed with DNP-Ascaris extract or DNP-ragweed antigen conjugates, effect of cyclic AMP and cyclic GMP on the B cell activation will be studied. We shall also study role of these systems on the release of T cell factor from carrier-primed cells.